Electric properties of carbon nano-structures having an extensive conjugated π-electron system (e.g. carbon nanotubes) have become of interest. Such carbon materials are envisaged to be developed particularly as high-efficiency electrode materials for use in micro-scale devices, large-scale batteries, etc. Among these devices, fuel cells require an electrode that can incorporate platinum. Therefore, a carbon nanostructure, which readily forms micropowder, is a promising candidate of the electrode.
According to common knowledge, graphene is a single layer isolated from graphite having a multi-layer structure. In other words, graphene has a very extensive conjugated n-electron system and conceivably has a single plane structure, which differs from the structures of other carbon nanostructures. Thus, various theoretical calculations have been conducted in relation to graphene so as to achieve high electrical conductivity from graphene.
Meanwhile, regarding the carbon nanowall production method, Patent Documents 1 and 2 disclose carbon nanowall production techniques which employ plasma. However, there has never been reported a process for producing graphene from liquid material.    Patent Document 1: Japanese Patent Application No. 2005-097113    Patent Document 2: Japanese Sai-Kohyo Patent Publication No. 2005/021430